Bulk packaging containers have found widespread use for storage and shipment of bulk goods, including hazardous materials. The bulk packaging containers assume many different forms. Among these forms are intermediate bulk containers (IBCs) and portable tanks. Requirements for these types of containers are outlined in various D.O.T. and F.D.A regulations and are particularly defined in 47 CFR Section 171.8.
Among IBCs, there include numerous types of designs. These include metal IBCs, which are constructed of metal, rigid plastic IBCs which are constructed of all plastic material, and composite IBCs which include a rigid outer packaging enclosing a plastic inner receptacle. The outer packaging may consist of, for example, a wire cage or the like. Rigid plastic IBCs are often more corrosion resistant to certain chemicals because of the lack of metal in their construction.
As with any product, cost is an important constraint. In the shipping industry, size and weight requirements are also important, as they impact on shipping costs. Rigid plastic IBCs or portable tanks may often produce the most advantageous combination among cost, size and weight.
Presently, there are available IBCs and portable tanks made of all polymeric materials. These articles include a pallet-like base and bottle mounted to the base. Both the bottle and the base are made by rotational molding. Due to necessities relating to rotational molding, the base tends to be substantially larger than desired. The larger size results in increases in costs, weight and size. Also, the use of rotational molding limits the type of resins that can be used in forming the base.
With previous designs of rigid plastic IBCs and portable tank bottles, the locations and sizes of molded openings or non-openings were limited specifically to those built into the rotational molding tool. Costly and time-consuming alterations were needed to the mold to change these combinations of molded-in openings. This limited the number of combinations of openings that could be offered to customers for reasonable cost, and in a short lead time.
IBCs and portable tanks are typically designed to be stacked during shipment and/or during storage. The rigid plastic designs often include stacking guides which helps to center the upper container over the lower container in a stack, and to help prevent the upper container from sliding off the lower container. The stacking guides are often molded integrally into the shape of the top of the bottle. In previous designs, the dimensions of the stacking guides have been several times greater than the wall thickness of the bottle. This creates a cavity on the interior upper surface of the bottle which is difficult to clean through the openings in the bottle. Given the constraints of cost and regulatory testing requirements, it is not feasible to provide openings so large that a worker could physically enter the bottle for cleaning.
Finally, in designing a bottle it is necessary to provide appropriate support to withstand horizontal forces of hoop stresses due to internal head pressure and also to withstand vertical downward forces of stacking loads without buckling. Any design must keep in mind the desire to utilize less plastic resin while producing an appropriate structural strength.
The present invention is directed to solving one or more of the problems discussed above in a novel and simple manner.